14,15-Dihydroxyeicosatrienoic acid, a soluble epoxide hydrolase metabolite in blood, is a predictor of anthracycline-induced cardiotoxicity - a hypothesis generating study

BACKGROUND

Early identification of patients susceptible to chemotherapy-induced cardiotoxicity could lead to targeted treatment to reduce cardiac dysfunction. Rats treated with doxorubicin (DOX), a chemotherapeutic agent, have increased cardiac expression of 14,15-dihydroxyeicosatrienoic acid (14,15-DHET), a bioactive lipid implicated in hypertension and coronary artery disease. However, the utility of 14,15-DHET as plasma biomarkers was not defined. The aim of this study is to investigate if levels of 14,15-DHET are an early blood biomarker to predict the subsequent occurrence of cardiotoxicity in cancer patients after chemotherapy.

METHODS

H9c2 rat cardiomyocytes were treated with DOX (1 μM) for 2 h and levels of 14,15-DHET in cell media was quantified at 2, 6 or 24 h in media after DOX treatment. Similarly, female Sprague-Dawley rats were treated with DOX for two weeks and levels of 14,15-DHET was assessed in plasma at 48 h and 2 weeks after DOX treatment. Changes in brain natriuretic peptide (BNP) mRNA, an early cardiac hypertrophy process, were determined in the H9c2 cells and rat cardiac tissue. Results were confirmed in human subjects by assessment of levels of 14,15-DHET in plasma of breast cancer patients before and after DOX treatment and left ventricular ejection fraction (LVEF), a clinical marker of cardiotoxicity.

RESULTS

Levels of 14,15-DHET in cell media and rat plasma increased ~ 3-fold and was accompanied with increase in BNP mRNA in H9c2 cells and rat cardiac tissue after DOX treatment. In matched plasma samples from breast cancer patients, levels of 14,15-DHET were increased in patients that developed cardiotoxicity at 3 months before occurrence of LVEF decrease.

CONCLUSIONS

Together, these results indicate that levels of 14,15-DHET are elevated prior to major changes in cardiac structure and function after exposure to anthracyclines. Increased levels of 14,15-DHET in plasma may be an important clinical biomarker for early detection of anthracycline-induced cardiotoxicity in cancer patients.

Levels of plasma glycan-binding auto-IgG biomarkers improve the accuracy of prostate cancer diagnosis

Strategies to improve the early diagnosis of prostate cancer will provide opportunities for earlier intervention. The blood-based prostate-specific antigen (PSA) assay is widely used for prostate cancer diagnosis but specificity of the assay is not satisfactory. An algorithm based on serum levels of PSA combined with other serum biomarkers may significantly improve prostate cancer diagnosis. Plasma glycan-binding IgG/IgM studies suggested that glycan patterns differ between normal and tumor cells. We hypothesize that in prostate cancer glycoproteins or glycolipids are secreted from tumor tissues into the blood and induce auto-immunoglobulin (Ig) production. A 24-glycan microarray and a 5-glycan subarray were developed using plasma samples obtained from 35 prostate cancer patients and 54 healthy subjects to identify glycan-binding auto-IgGs. Neu5Acα2-8Neu5Acα2-8Neu5Acα (G81)-binding auto-IgG was higher in prostate cancer samples and, when levels of G81-binding auto-IgG and growth differentiation factor-15 (GDF-15 or NAG-1) were combined with levels of PSA, the prediction rate of prostate cancer increased from 78.2% to 86.2% than with PSA levels alone. The G81 glycan-binding auto-IgG fraction was isolated from plasma samples using G81 glycan-affinity chromatography and identified by N-terminal sequencing of the 50 kDa heavy chain variable region of the IgG. G81 glycan-binding 25 kDa fibroblast growth factor-1 (FGF1) fragment was also identified by N-terminal sequencing. Our results demonstrated that a multiplex diagnostic combining G81 glycan-binding auto-IgG, GDF-15/NAG-1 and PSA (≥ 2.1 ng PSA/ml for cancer) increased the specificity of prostate cancer diagnosis by 8%. The multiplex assessment could improve the early diagnosis of prostate cancer thereby allowing the prompt delivery of prostate cancer treatment.

Abstract 5436: Identification of early lung cancer miRNA biomarkers using qRT-PCR and novel label-free nanoarray technology

Whereas over 75% of lung cancer patients are diagnosed at an advanced or metastatic stage and their 5-year survival rate is <5%, patients diagnosed at an early stage, Stage I, have ~70% 5-year survival rate. In the present study, Stage I lung cancer miRNA biomarkers were identified using qRT-PCR and novel label-free facile nanoarray technology for early lung cancer detection. Total RNA from human A549 lung and ACHN kidney cancer cell lysates and media were isolated and qRT-PCR/Taqman® analyses (two-step RT-PCR) were carried out for 8 miRNA lung cancer biomarker candidates. The 8 miRNA levels were normalized by the miR16 level (no change reported in lung cancer). Ratios of miR486/miR16 and miR29c/miR16 increased ~10-fold in A549 lung cancer cell lysates and media compared with those in ACHN kidney cells. Total RNA fractions were isolated from 11 healthy subjects, 21 Stage I and 19 Stage II/III adenocarcinoma and 5 squamous lung cancer patients and levels of the 8 miRNAs were measured by qRT-PCR/Taqman® analysis (in total, 1,026 analyses) and normalized by the miR16 level. miR486 levels were up-regulated (p=0.02) and miR203 (p=0.0005) and miR205 (p=0.041) levels were down-regulated in Stages I and II/III adenocarcinoma. Whereas miR122 and miR29c were not detected in serum samples from the majority of healthy subjects, the miRNAs were expressed in 82% and 71%, respectively, of Stage I and 90% and 100%, respectively, of Stages II/III lung cancer patients. A novel label-free facile 90 nm (diameter) miRNA nanowell technology was developed. Electrochemical analyses of the early lung cancer biomarker candidates, miR486 and miR29c, and, an internal control, miR16, were carried out using various concentrations of miRNA standards (0 to 100 fM) with biotinylated cDNA captured by streptavidin coated on the nanogold surface. The Nyquist plots showed a dose-dependent increase in impedance (-Z” kohm) and sensitivity of the miRNA nanowell electrochemical technology was ≤1 fM. The impedance level obtained with miR29c in A549 lung cancer cell media was ~2.8-fold higher (mean value ± SD, 163.9 ± 32.8 kohm) compared with ACHN kidney cancer cell media (60.8 ± 33.1 kohm) by 90 nm nanowell analysis (p=0.000019). Electrochemical analyses of a serum sample obtained from a lung cancer patient revealed that miR486 and miR29c levels were ~2-fold (p=0.0031) and 9-fold (p=0.0006) higher, respectively, compared to the pooled human control sera. This result agreed with the result obtained by qRT-PCR/Taqman® analysis of human serum samples. Our results suggest that miR486 and miR203 levels up- and down-regulated, respectively, in lung cancer serum samples are biomarkers for early (Stage I) lung cancer diagnosis. Supported by NCI SBIR Phase I contract, N261201500040C (Topic 337).

Citation Format: Julia M. Santos, Aby Joiakim, David A. Putt, Pilar Herrera-Fierro, Vishva Ray, Alan Dombokowski, Guoan Chen, David G. Beer, Hyesook Kim. Identification of early lung cancer miRNA biomarkers using qRT-PCR and novel label-free nanoarray technology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5436. doi:10.1158/1538-7445.AM2017-5436

Differential BPA levels in sewage wastewater effluents from metro Detroit communities

The endocrine disruptor Bisphenol A (BPA) is ubiquitous in both aquatic and surface sediment environments because it is continuously released into sewage wastewater effluent. The measurement of BPA at wastewater treatment plants is rarely performed even though the United States Environmental Protection Agency (EPA) states that current levels of environmental BPA could be a threat to aquatic organisms. Therefore, the aims of this study were to measure BPA levels in sewage wastewater at different collection points over a 1-year period and to compare the levels of BPA to 8-isoprostane, a human derived fatty acid, found in sewage wastewater. We analyzed pre-treated sewage samples collected from three source points located in different communities in the metropolitan Detroit area provided by the Detroit Water and Sewerage Department. Human urine samples were also used in the study. BPA and 8-isoprostane were measured using ELISA kits from Detroit R&D, Inc. BPA levels from the same collection point oscillated more than 10-fold over 1 year. Also, BPA levels fluctuated differentially at each collection point. Highly fluctuating BPA values were confirmed by LC/MS/MS. The concentration of BPA in sewage wastewater was ~100-fold higher than the concentration of 8-isoprostane, while urinary concentration was ~20-fold higher. Thus, BPA levels discharged into the sewage network vary among communities, and differences are also observed within communities over time. The difference in BPA and 8-isoprostane levels suggest that most of the BPA discharged to sewage wastewater might be derived from industries rather than from human urine. Therefore, the continuous monitoring of BPA could account for a better regulation of BPA release into a sewage network.

Epidermal Growth Factor Receptor Kinase Inhibitors Synergize with TCDD to Induce CYP1A1/1A2 in Human Breast Epithelial MCF10A Cells

CYP1A1 and CYP1A2 are transcriptionally activated in the human normal breast epithelial cell line MCF10A following exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Shifting MCF10A cultures to medium deficient in serum and epidermal growth factor (EGF) caused rapid reductions in the activated (i.e., phosphorylated) forms of extracellular regulated kinases (ERKs) and the epidermal growth factor receptor (EGFR). Shifting to serum/EGF-deficient medium also enhanced TCDD-mediated induction of cytochrome P450 (CYP)1A1 Treatment of cells cultured in complete medium with the EGFR inhibitors gefitinib (Iressa), AG1478, and CI-1033 resulted in concentration-dependent reductions of active EGFR and ERKs, and increased CYP1A1 mRNA content ∼3- to 18-fold above basal level. EGFR inhibitors synergized with TCDD and resulted in transient CYP1A1 and CYP1A2 mRNA accumulations ∼8-fold greater (maximum at 5 hours) than that achieved with only TCDD. AG1478, gefitinib, and TCDD individually induced small increases (∼1.2- to 2.5-fold) in CYP1A1 protein content but did not cause additive or synergistic accumulations of CYP1A1 protein when used in combination. The mitogen-activated protein kinase kinase inhibitor PD184352 inhibited ERK and EGFR activation in a concentration-dependent fashion without causing CYP1A1 mRNA accumulation. However, cotreatment with PD184352 potentiated TCDD-mediated CYP1A1 induction. TCDD-mediated induction of CYP1A1 in MCF7-TET on-EGFR cells, a MCF7 variant in which EGFR expression can be controlled, was not affected by the activity status of EGFR or ERKs. Hence, EGFR signaling mutes both basal and ligand-induced expression of two aryl hydrocarbon receptor-responsive P450s in MCF10A cultures. However, these effects are cell context-dependent. Furthermore, CYP1A1 mRNA and protein abundance are not closely coupled in MCF10A cultures.

Abstract A26: Effects of O-GlcNAcase inhibitors on O-GlcNAcylated c-myc expression in MCF-7 cells

Protein N-acetylglucosamine modification (O-GlcNAcylation) plays a critical role in cell-cycle regulation, apoptosis and signal transduction. Thr-58 of c-myc, a mutational hot spot in lymphomas, is a site for both phosphorylation (primed by Ser-62 phosphorylation) and O-GlcNAcylation, which are conserved among human rat and mouse. Whereas Thr-58O-GlcNAcylation induces ubiquitin-dependent c-myc degradation, Thr-58/Ser-62 phosphorylation increases c-myc stability and thus induces invasiveness and tumorigenesis of MCF-7 human breast cancer cells.

c-Myc antibodies specific for (a) Thr-58-O-GlcNAcylation, (b) Thr-58-unmodification and (c) Thr-58/Ser-62 phosphorylation were produced and specificities of the antibodies have been characterized by Western blot analyses using BSA conjugated with synthetic peptides containing the O-GlcNAcylated, unmodified and phosphorylated sites of c-myc. Western blot analysis of MCF-7 cells revealed that, whereas ~68 kDa Thr-58-O-GlcNAcylated c-myc proteins were primarily detected in the nuclear fraction, the 65-68 kDa Thr-58/Ser-62 phosphorylated and 65 kDa and 40 kDa Thr-58 unmodified c-myc proteins were expressed in both nuclear and cytosolic fractions.

When MCF-7 cells were treated with 1% DMSO, 2 mM ketoconazole, a medicine-like human and bacterial β-N-acetylglucosaminidase (O-GlcNAcase) inhibitor, or 2 mM streptozotocin (STZ), an irreversible inhibitor of O-GlcNAcase, dissolved in DMSO (final concentration, 1%) for 4 hr, Thr-58-O-GlcNAcylated c-myc protein levels in nuclear and total cell lysates increased after 2 mM ketoconazole treatment but not with STZ treatment. Thr-58/Ser-62 phosphorylated protein levels did not change after either ketoconazole or STZ treatments. Treatment of the cells with 1% DMSO, 2 mM ketoconazole, buspirone or acetazolamide dissolved in DMSO (final concentration, 1%) or N6-methyladenosine 5'-monophosphate (dissolved in media), a medicine-like O-GlcNAcase inhibitor, for 4 hr revealed that Thr-58-O-GlcNAcylated c-myc protein levels in nuclear lysates increased only when the cells were treated with 2 mM ketoconazole. None of the O-GlcNAcase inhibitors including ketoconazole treatments changed levels of c-myc proteins unmodified at the Thr-58 site or phosphorylated at the Thr-58/Ser-62 sites. Whereas treatment of the MCF-7 cells with 2 mM STZ and N6-methyladenosine 5'-monophosphate failed to induce cell death and treatment with 2 mM buspirone and acetazolamide induced minimal cell death, 2 mM ketoconazole treatment, which dramatically increased Thr-58-O-GlcNAcylated c-myc protein levels, induced severe cell death.

Subsequent lactate dehydrogenase (LDH) cytotoxicity assays demonstrated that the ketoconazole treatment increased cell death in MCF-7 cells 84% higher than in MCF10A non-cancerous cells by lactate dehydrogenase (LDH) cytotoxicity assays. Dose-dependent cell proliferation assays were carried out by treatment of the cells with and without 10, 20, 50 or 100 µM ketoconazole dissolved in DMSO for 72 hr, staining the cells with 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl-tetrazolium bromide (MTT). The ketoconazole treatment inhibited cell proliferation of the MCF-7 cells by 60% and 90% at 50 and 100 µM, respectively (p < 0.05).

These results suggest that, in MCF-7 cells, ketoconazole, a medicine-like O-GlcNAcase inhibitor, dramatically increased Thr-58-O-GlcNAcylated c-myc proteins, which coincided with increased cell death and inhibited cell proliferation. Supported by NCI SBIR Phases I and II Contracts N261201100073C and N261201300058C.

Citation Format: Hyesook Kim, So Hee Kim, Aby Joiakim, David Kaplan, David Putt. Effects of O-GlcNAcase inhibitors on O-GlcNAcylated c-myc expression in MCF-7 cells. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr A26.

Abstract 1230: Detection of increased O-GlcNAcylated p53 levels in MCF-7 cells after O-GlcNAcase inhibitor treatment using antibodies specific for Ser-149-O-GlcNAcylated p53 proteins

Protein O-GlcNAcylation (N-acetylglucosamine modification) plays a critical role in cell-cycle regulation, apoptosis and signal transduction. Most serine (Ser) and threonine (Thr) sites for O-GlcNAcylation are on or near to phosphorylation sites, which creates a system of mutual elimination. O-GlcNAcylation of p53, a tumor suppressor protein, at Ser-149 prevents p53 degradation and stabilizes p53 proteins expressed in MCF-7 human breast cancer cells whereas phosphorylation of the p53 at Thr-155 induces ubiquitin-dependent degradation, which decreases p53 levels. Accumulation of the p53 protein in cancer cells induces arrest of cell growth and apoptosis in response to DNA damage. Ser-149 site-specific anti-peptide antibodies have been produced using KLH conjugated with p53 peptides with and without O-GlcNAcylation at Ser-149 by immunization of rabbits for polyclonal and mice for monoclonal antibodies. Whereas polyclonal antibodies and hybridoma media for O-GlcNAcylated p53 cross-reacted with BSA conjugated with Ser-149-O-GlcNAcylated p53 peptides in ELISA or Western blot analysis, the antibodies did not cross-react with BSA conjugated with p53 peptides without O-GlcNAcylation. Anti-peptide polyclonal antibodies produced for the unmodified p53 peptides did not cross-react with BSA conjugated with Ser-149 O-GlcNAcylated p53 peptides. Using the hybridoma media for Ser-149-O-GlcNAcylated p53, Western blot analysis was carried out with nuclear lysates and cytosol-containing supernatant obtained from MCF10A (normal breast cancer cell line) and MCF-7 cells. It was found that, in MCF-10A cells, Ser-149-O-GlcNAcylated p53 proteins (∼55 kDa) were minimally expressed in the nuclear fraction but highly expressed in the cytosolic fraction whereas, in MCF-7 cells, the level of cytosolic Ser-149-O-GlcNAcylated p53 protein was low compared with the level in MCF-10A cells. MCF-7 cells were treated for 24 hr with 1% DMSO or 2 mM β-N-acetylglucosaminidase (O-GlcNAcase) inhibitor, acetazolamide, dissolved in DMSO and levels of Ser-149-O-GlcNAcylated p53 were determined by Western blot analysis using antibodies for the Ser-149-O-GlcNAcylated p53. Whereas the level of O-GlcNAcylated p53 did not increase after 1% DMSO treatment, the level dramatically increased after treatment of acetazolamide in 1% DMSO and induced cell death. Our results showed that acetazolamide treatment increased Ser-149-O-GlcNAcylated p53 level and induced cell death in MCF-7 cells, which may decrease invasiveness of the breast cancer cells. Supported by NCI SBIR Phases I and II Contracts No. N261201100073C and N261201300058C.

Citation Format: Hyesook Kim, So Hee KIm, Aby Joiakim, David Kaplan, Sung Hun Bae, David Putt. Detection of increased O-GlcNAcylated p53 levels in MCF-7 cells after O-GlcNAcase inhibitor treatment using antibodies specific for Ser-149-O-GlcNAcylated p53 proteins. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1230. doi:10.1158/1538-7445.AM2015-1230

Abstract 3513: Ketoconazole-induced O-GlcNAcylated c-Myc expression and inhibition of cell proliferation in cancers

Protein N-acetylglucosamine modification (O-GlcNAcylation) plays a critical role in cell-cycle regulation, apoptosis and signal transduction. Thr-58 of c-Myc, a mutational hot spot in lymphomas, is a site for both phosphorylation (primed by Ser-62 phosphorylation) and O-GlcNAcylation. Whereas Thr-58 O-GlcNAcylation induces ubiquitin-dependent c-Myc degradation, Thr-58/Ser-62 phosphorylation increases c-Myc stability and thus induces invasiveness and tumorigenesis of MCF-7 human breast cancer cells. Using form-specific antibodies for Thr-58-O-GlcNAcylated c-Myc, Western blot analysis was carried out and found that Thr-58-O-GlcNAcylated c-Myc proteins were detected primarily in the nuclear fraction as 68 kDa proteins. MCF-7 cells were treated for 4 hr with 1% DMSO or 2 mM ketoconazole [β-N-acetylglucosaminidase (O-GlcNAcase) inhibitor, dissolved in DMSO]. Western blot analysis of nuclear lysates of MCF-7 cells revealed that the levels of Thr-58-O-GlcNAcylated c-Myc dramatically increased after ketoconazole treatment. Thr-58-O-GlcNAcylated c-Myc levels also increased in the nuclear lysates of Mia Paca-2 and SW480 cells treated with 50 µg/ml for 48 hours. The ketoconazole treatment increased cell death in MCF-7 cells 84% higher than in MCF10A non-cancerous cells by lactate dehydrogenase (LDH) cytotoxicity assays. Treatment with 50 µg/ml ketoconazole for 72 hr inhibited cell proliferation of colon cancer cells, SW480 and HT29, by 63.3% and 67.4%, respectively, lung cancer cells, H1437 and A549, by 44.9% and 51.3%, respectively, and a pancreatic cancer cell, Mia Paca-2, by 60.2% in a dose-dependent manner. These results demonstrated that treatment of ketoconazole inhibited the proliferation of MCF-7 breast cancer cells as well as colon, lung and pancreatic cancer cells. Wound healing assays were carried out to verify the inhibition of cell migration. Whereas 55.3% of Mia Paca-2 cells migrated toward a scratched field after 24-hr treatment, only 11.6% of the cells migrated after treatment with 100 µg/ml ketoconazole. PANC-1 cells, which failed to increase Thr-58-O-GlcNAcylated c-Myc expression and cell proliferation after ketoconazole treatment, showed no significant difference of cell migration after 24 hr with 100 µg/ml ketoconazole treatment. Surprisingly, colon cancer cells, SW480 and HT29, showed an inhibition of invasiveness as evidenced by the inhibition of cell proliferation and cell migration after treatment with 100 µg/ml ketoconazole. Collectively, our results demonstrated that treatment of ketoconazole, an O-GlcNAcase inhibitor, increased Thr-58-O-GlcNAcylated c-Myc level and inhibited cell proliferation in MCF-7, SW480, HT29, H1437, A549 and Mia Paca-2 cells, which may decrease invasiveness and migration of the breast, colon, lung and pancreatic cancer cells. Supported by NCI SBIR Phase II Contract No. HHSN261201300058C.

Citation Format: So Hee Kim, Eun-Sin Du, Aby Joiakim, Sung-Su Park, David Kaplan, David Putt, Hyesook Kim. Ketoconazole-induced O-GlcNAcylated c-Myc expression and inhibition of cell proliferation in cancers. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3513. doi:10.1158/1538-7445.AM2014-3513

Abstract LB-58: Production of Thr-58-O-GlcNAcylated c-myc antibodies and detection of increased O-GlcNAcylated c-myc levels in MCF-7 cells after ketoconazole treatment

Protein O-GlcNAcylation (N-acetylglucosamine modification) plays a critical role in cell-cycle regulation, apoptosis and signal transduction. Most serine (Ser) and threonine (Thr) sites for O-GlcNAcylation are on or near to phosphorylation sites, which creates a system of mutual elimination. Thr-58 of c-myc, a mutational hot spot in lymphomas, is a site for both phosphorylation (primed by Ser-62 phosphorylation) and O-GlcNAcylation. Whereas Thr-58 O-GlcNAcylation induces ubiquitin-dependent c-myc degradation, Thr-58/Ser-62 phosphorylation increases c-myc stability and invasiveness and tumorigenesis of MCF-7 human breast cancer cells. Thr-58 site-specific anti-peptide antibodies have been produced by immunization of rabbits with KLH conjugated with c-myc peptides with and without Thr-58 O-GlcNAcylation. Whereas the antibodies for O-GlcNAcylated c-myc cross-reacted with BSA conjugated with Thr-58-O-GlcNAcylated c-myc peptides in ELISA and Western blot analysis, the antibodies did not cross-react with BSA conjugated with c-myc peptides without O-GlcNAcylation. Anti-peptide antibodies produced for the unmodified c-myc peptides did not cross-react with BSA conjugated with Thr-58-O-GlcNAcylated c-myc peptides. Using the antibodies for Thr-58-O-GlcNAcylated c-myc, Western blot analysis was carried out with nuclear lysates and cytosol-containing supernatant obtained from MCF-7 cells and it was found that Thr-58-O-GlcNAcylated c-myc proteins were minimally expressed in the cytosolic fraction but highly expressed in the nuclear fraction. Whereas c-myc proteins without Thr-58-O-GlcNAcylation in the nuclear fraction were detected primarily as 65 kDa proteins in Western blot analyses, Thr-58-O-GlcNAcylated c-myc proteins in the nuclear fraction were detected primarily as 68 kDa proteins. MCF-7 cells were treated for 4 hr with 1% DMSO and 2 mM β-N-acetylglucosaminidase (O-GlcNAcase) inhibitors (buspirone or ketoconazole) dissolved in DMSO and levels of Thr-58-O-GlcNAcylated and unmodified c-myc were determined by Western blot analysis using antibodies for the Thr-58-O-GlcNAcylated or unmodified c-myc. Whereas the O-GlcNAcylated c-myc level did not increase after buspirone treatment, the level dramatically increased after ketoconazole treatment. The Thr-58-unmodified c-myc protein level failed to increase after 2 mM ketoconazole treatment. The ketoconazole treatment increased cell death in MCF-7 cells 84% higher than in MCF10A non-cancerous cells as evidenced by lactate dehydrogenase (LDH) cytotoxicity assays. Our results showed that ketoconazole treatment increased Thr-58-O-GlcNAcylated c-myc level and induced cell death in MCF-7 cells, which may decrease invasiveness of the breast cancer cells. Supported by NCI SBIR Phase I Contract No. HHSN261201100073C.

Citation Format: Hyesook Kim, Sohee Kim, Aby Joiakim, David Kaplan, David Putt. Production of Thr-58-O-GlcNAcylated c-myc antibodies and detection of increased O-GlcNAcylated c-myc levels in MCF-7 cells after ketoconazole treatment. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-58. doi:10.1158/1538-7445.AM2013-LB-58

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

p-Anilinoaniline enhancement of dioxin-induced CYP1A1 transcription and aryl hydrocarbon receptor occupancy of CYP1A1 promoter: role of the cell cycle

The aryl hydrocarbon receptor (AhR) is targeted by ubiquitination for degradation by the proteasome shortly after its activation by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In silico screening identified p-anilinoaniline (pAA) as a putative inhibitor of an E2 ligase that partners with an E3 ligase implicated in AhR ubiquitination. We investigated whether pAA could modify AhR-dependent activation of its target gene CYP1A1. pAA (1-200 μM) alone did not affect AhR content, or stimulate CYP1A1 mRNA accumulation in human mammary epithelial MCF10A cultures. However, pretreatment with ≥100 μM pAA suppressed TCDD-induced CYP1A1 activation and AhR degradation via its functioning as an AhR antagonist. At a lower concentration (25 μM), pAA cotreatment increased TCDD-induced CYP1A1 mRNA accumulation, without inhibiting AhR turnover or altering CYP1A1 mRNA half-life. Whereas TCDD alone did not affect MCF10A proliferation, 25 μM pAA was cytostatic and induced a G(1) arrest that lasted ∼7 h and induced an S phase arrest that peaked 5 to 8 h later. TCDD neither affected MCF10A cell cycle progression nor did it alter pAA effects on the cell cycle. The magnitude of CYP1A1 activation depended upon the time elapsed between pAA pretreatment and TCDD addition. Maximal AhR occupancy of the CYP1A1 promoter and accumulation of CYP1A1 heterogeneous nuclear RNA and mRNA occurred when pAA-pretreated cultures were exposed to TCDD in late G(1) and early/mid S phase. TCDD-mediated induction of CYP2S1 was also cell cycle-dependent in MCF10A cultures. Similar studies with HepG2 cultures indicated that the cell cycle dependence of CYP1A1 induction is cell context-dependent.

The chemotherapeutic agents XK469 (2-{4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy}propionic acid) and SH80 (2-{4-[(7-bromo-2-quinolinyl)oxy]phenoxy}propionic acid) inhibit cytokinesis and promote polyploidy and induce senescence

The therapeutic usefulness of the quinoxaline derivatives XK469 (2-{4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy}propionic acid) and SH80 (2-{4-[(7-bromo-2-quinolinyl)oxy]phenoxy}propionic acid) has been attributed to their abilities to induce G(2)/M arrest and apoptotic or autophagic cell death. Concentrations of XK469 or SH80 > or = 5 microM were cytostatic to cultures of the normal murine melanocyte cell line Melan-a. Higher concentrations caused dose-dependent cytotoxicity. Concentrations > or =10 microM provoked dramatic morphological changes typified by marked increases in cell size and granularity. XK469/SH80-treated cultures accumulated tetraploid (4N) DNA-containing cells within 24 h of treatment, an 8N population within 3 days, and a 16N population within 5 days. Increases in ploidy correlated with the appearance of multinucleated cells. Under no circumstances did cells exhibit evidence of furrow formation. Both drugs suppressed cytokinesis in additional mammalian cell lines. Cytotoxic concentrations of XK469 elevated DEVDase activities (a measure of procaspase-3/7 activation) and enhanced cellular staining by a fluorescent analog of the pan caspase inhibitor valine-alanine-aspartic acid-fluoromethyl ketone within 48 to 96 h of treatment. Within 48 h of treatment, cytostatic and cytotoxic concentrations of XK469 elevated p21 contents, reduced Bcl-2 and Bcl-XL contents, and induced autophagy, as monitored by the accumulation of phosphatidylethanolamine-modified cleavage product of microtubule-associated protein light chain 3 (LC3-II). Cultures treated with > or =10 microM XK469 or SH80 for 5 days could not be induced to divide upon removal of drugs. Such cultures maintained high LC3-II contents, exhibited reduced cyclin E and D1 contents, and extensively expressed senescence-associated beta-galactosidase within 14 to 17 days of cessation of drug treatment. Hence, XK469 and SH80 inhibit cytokinesis, promote polyploidy, and induce senescence in Melan-a cells.

Aryl hydrocarbon receptor modulation of tumor necrosis factor-alpha-induced apoptosis and lysosomal disruption in a hepatoma model that is caspase-8-independent

Recent studies suggest that the aryl hydrocarbon receptor (AhR) modulates susceptibilities to some pro-apoptotic agents. AhR-containing murine hepatoma 1c1c7 cultures underwent apoptosis following exposure to tumor necrosis factor-alpha (TNFalpha) + cycloheximide (CHX). In contrast, Tao cells, an AhR-deficient variant of the 1c1c7 line, were refractory to this treatment. AhR sense/antisense transfection studies demonstrated that AhR contents influenced susceptibility to the pro-apoptotic effects of TNFalpha + CHX. 1c1c7 cells and all variants expressed comparable amounts of TNF receptor-1 and TRADD. However, no cell line expressed FADD, and consequently pro-caspase-8 was not activated. AhR content did not influence JNK and NF-kappaB activation. However, Bid and pro-caspase-9, -3, and -12 processing occurred only in AhR-containing cells. Analyses of cathepsin B and D activities in digitonin-permeabilized cultures and the monitoring of cathepsin B/D co-localization with Lamp-1 indicated that TNFalpha + CHX disrupted late endosomes/lysosomes in only AhR-containing cells. Stabilization of acidic organelles with 3-O-methylsphingomyelin inhibited TNFalpha + CHX-induced apoptosis. The cathepsin D inhibitor pepstatin A suppressed in vitro cleavage of Bid by 1c1c7 lysosomal extracts. It also delayed the induction of apoptosis and partially prevented Bid cleavage and the activation of pro-caspases-3/7 in cultures treated with TNFalpha + CHX. Similar suppressive effects occurred in cultures transfected with murine Bid antisense oligonucleotides. These studies showed that in cells where pro-caspase-8 is not activated, TNFalpha + CHX can initiate apoptosis through lysosomal disruption. Released proteases such as cathepsin D trigger the apoptotic program by activating Bid. Furthermore, in the absence of exogenous ligand, the AhR modulates lysosomal disruption/permeability.

Differential susceptibilities of murine hepatoma 1c1c7 and Tao cells to the lysosomal photosensitizer NPe6: influence of aryl hydrocarbon receptor on lysosomal fragility and protease contents

Irradiation of murine hepatoma 1c1c7 cultures presensitized with N-aspartyl chlorin e6 (NPe6) caused lysosomal disruption and apoptosis. Tao cells, a variant of the 1c1c7 line having lower aryl hydrocarbon receptor (AhR) contents, were resistant to the pro-apoptotic effects of NPe6 in the same photodynamic therapy protocol. Colony-forming assays were used to establish light dose-dependent and NPe6 concentration-dependent cytotoxicity curves. Lysosomal breakage and cell survival paralleled one another in both cell types. When analyzed at comparable lethal dose conditions, the onset of apoptosis was delayed, and the magnitude of the apoptotic response was muted in Tao cells, as assessed by morphology, annexin V binding, caspase-3 activities, and analyses of Bid, procaspase-9, and pro-caspase-3 cleavage. In contrast, the kinetics/magnitude of pro-caspase-3 activation in the two cell lines were identical after exposure to HA14 -1 or Jo2 antibody, inducers of the intrinsic and extrinsic apoptotic pathways, respectively. Tao endosomal/lysosomal extracts contained approximately 50%, 35%, and 55% of the Bid cleavage and cathepsin B and D activities of 1c1c7 endosomes/lysosomes, respectively. Western blot analyses confirmed reduced cathepsin B/D contents in Tao cells. Analyses of 1c1c7/Tao variants engineered to express antisense/sense AhR constructs suggested that endosomal/lysosomal cathepsin B and D content, but not whole cell content, correlated with AhR expression. These studies provide a mechanism for the resistance of Tao cultures to the proapoptotic effects of a protocol causing targeted disruption of lysosomes. They also suggest that the AhR, in the absence of exogenous ligand, may affect the trafficking/processing of proteases normally found in endosomes/lysosomes.

THE JUN N-TERMINAL KINASE INHIBITOR SP600125 IS A LIGAND AND ANTAGONIST OF THE ARYL HYDROCARBON RECEPTOR

Exposure of the immortalized human breast epithelial cell line MCF10A to the Jun N-terminal kinase (JNK) inhibitor anthra[1,9-cd]pyrazol-6(2H)-one (SP600125) suppressed, in a concentration-dependent manner (IC50 is approximately 2 microM), the induction of CYP1A1 by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Cotreatment with SP600125 also suppressed the accumulation of TCDD-induced nuclear aryl hydrocarbon receptor (AhR)-DNA complexes, as assessed by electrophoretic mobility shift assays. Concentrations of SP600125 < or = 50 microM did not transform the AhR into a DNA-binding species when added to rat liver cytosol. However, addition of SP600125 to cytosol just before TCDD addition completely suppressed AhR transformation and DNA binding (IC50 approximately 7 microM). Sucrose gradient analyses using rat liver and murine hepatoma 1c1c7 extracts demonstrated that SP600125 competed with TCDD for binding to the AhR. These results suggest that SP600125 is an AhR ligand and functions as an AhR antagonist at concentrations used to pharmacologically inhibit JNK.

Suppression of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-mediated CYP1A1 and CYP1B1 induction by 12-O-tetradecanoylphorbol-13-acetate: role of transforming growth factor beta and mitogen-activated protein kinases

The phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) enhances or suppresses the transcriptional activation of CYP1A1 by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in a cell/tissue-specific manner. The basis for these effects is not known. Exposure of the immortalized human breast epithelial cell line MCF10A-Neo to TPA at the time of, or up to 12 hr prior to, the addition of TCDD strongly suppressed the transcriptional activation of CYP1A1 and CYP1B1 (IC(50) approximately 0.5 nM). A recent study (Carcinogenesis 2000;21:1303-12) demonstrated that TPA-treated MCF10A-Neo cells rapidly activate the latent transforming growth factor beta (TGFbeta) in the serum used to supplement the culture medium. The suppressive effects of TPA on CYP1A1 induction by TCDD in MCF10A-Neo cultures could be partially suppressed by: (a) co-incubation of TCDD + TPA-treated cultures with a neutralizing TGFbeta pan antibody; (b) prior removal of latent TGFbeta from the culture medium; or (c) switching cultures to serum- and growth factor-free medium immediately before the addition of TPA and TCDD. Exposure of cultures to TPA 24-48 hr prior to subsequent TPA + TCDD treatment not only inhibited the suppressive effects of TPA, but markedly enhanced CYP1A1 mRNA accumulation. TPA caused a rapid and protracted activation of extracellular signal-regulated kinases (ERKs). Pretreatment of cultures with the mitogen-activated protein kinase kinase (MEK) inhibitor PD184352 [2-(2-chloro-4-iodo-phenylamino)-N-cyclopropyl-methoxy-3,4-difluoro-benzamide] completely inhibited ERK activation by TPA. However, PD184352 did not prevent the suppressive effects of TPA on CYP1A1 activation by TCDD. These studies demonstrate that TPA initiates protein kinase C-dependent, ERK-independent processes that suppress CYP1A1 activation by TCDD in MCF10A-Neo cells. Furthermore, TGFbeta mediates a small portion of this suppressive activity.

Suppression of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-mediated aryl hydrocarbon receptor transformation and CYP1A1 induction by the phosphatidylinositol 3-kinase inhibitor 2-(4-morpholinyl)-8-phenyl-4H-1- benzopyran-4-one (LY294002)

Numerous flavonoids are ligands of the aryl hydrocarbon receptor (AHR) and function as AHR antagonists and/or agonists. LY294002 [2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one] is a widely used inhibitor of phosphatidylinositol 3-kinase (PI 3-kinase), and is structurally related to members of the flavonoid family. Concentrations of LY294002 >/= 10 microM were cytostatic, but not cytotoxic, to cultures of the immortalized human breast epithelial cell line MCF10A-Neo. Treatment of MCF10A-Neo cultures with the AHR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) stimulated the transcriptional activation of CYP1A1, as monitored by measurements of steady-state CYP1A1 mRNA. Pretreatment of cultures with >/= 10 microM LY294002 suppressed the TCDD activation of CYP1A1 (IC(50) approximately 10 microM). Electrophoretic mobility shift assays employing rat liver cytosol demonstrated that concentrations of LY294002 </= 400 microM did not transform the AHR into a DNA-binding species. However, the addition of LY294002 to cytosol just prior to TCDD addition completely suppressed AHR transformation by TCDD (IC(50) approximately 35 microM). The PI 3-kinase inhibitor Wortmannin was weakly cytostatic, but not cytotoxic to MCF10A-Neo cultures at concentrations </= 500 nM. Exposure of cultures to Wortmannin (10-500 nM) did not suppress TCDD activation of CYP1A1. Analyses of the phosphorylation status of Akt-1, an in vivo substrate of PI 3-kinase, demonstrated that concentrations of LY294002 >/= 50 microM and Wortmannin >/= 10 nM completely suppressed PI 3-kinase activity. Hence, the ability of LY294002 to suppress TCDD-dependent activation of CYP1A1 is unrelated to PI 3-kinase inhibition. Instead, this activity reflects LY294002 functioning as an AHR antagonist. Furthermore, most of the cytostatic activity of LY294002 towards MCF10A-Neo cells is unrelated to the inhibition of PI 3-kinase.

Differential growth factor responses of epithelial cell cultures derived from normal human prostate, benign prostatic hyperplasia, and primary prostate carcinoma

Because of a lack of information of the optimum nutritional requirements, epithelial cells derived from normal human prostate and prostate tumors have been difficult to propagate in vitro, which hinders research in prostate carcinogenesis. In an effort to establish optimum nutritional conditions and differences in growth characteristics of normal human prostate (NP), benign prostatic hyperplasia (BPH), and prostatic carcinoma (PCA), we have compared the effects of several growth factors on cell proliferation and elucidated growth properties of low passage epithelial cells derived from NP, BPH, and PCA of an African-American patient. Primary and low passage cultures were propagated in serum-free keratinocyte basal medium (KBM) supplemented with insulin (5 micrograms/ml), hydrocortisone (0.5 microgram/ml), epidermal growth factor (EGF, 10 ng/ml), bovine pituitary extract (BPE; 50 micrograms/ml), cholera toxin (10 ng/ml), and antibiotics. Almost all NP, BPH, and PCA cells were positive for cytokeratins and prostate-specific antigen (PSA). The NP, BPH, and PCA cells were essentially diploid and lacked mutations in c-K-ras and c-Ha-ras oncogenes, and p53 tumor suppressor gene. However, they exhibited progressively accelerating growth parameters. The population doubling times of NP, BPH and PCA were 51 hr, 37 hr, and 29 hr, respectively; their saturation densities were 2.9 x 10(4)/cm2, 3.3 x 10(4)/cm2, and 7.2 x 10(4)/cm2, respectively. The NP and BPH cells required all of the growth factors in the medium, as deletion of any one of the above factors strongly inhibited their growth. The PCA cells, however, were independent of EGF and hydrocortisone. PC-3, an established human prostate cancer cell line, was independent of the growth factors tested. Fetal bovine serum (FBS) inhibited the growth of NP, BPH and PCA cells. In contrast, FBS stimulated the growth of the PC-3 cells in a concentration-dependent manner. These results indicate that in the absence of any apparent karyotype alterations and mutations in c-K-ras, c-Ha-ras and p53 genes, epithelial cells derived from NP, BPH, and PCA exhibit significant differences in their growth properties and responses to growth factors. These variations may represent early changes involved in prostate cancer, while gene mutations and cytogenetic alterations occur in advanced and/or metastatic tumors.